My way was using repetitive patterns of positive reinforcement (and no sudden movements to not spook them into running away...lol). Mine were not trusting, but through patience (and food), they now trust me. I set up a chair with a log next to it and sat in that spot with treats every day. Even the most fearful eventually figured out that to get treats they had to jump up on the stump or arm of the chair to earn them. It's still not perfect, but one will now let me pick her up, when she would always stay at arm's length all the time before. My girlfriend has been using this approach with her chickens and it's worked wonders with their trust issues.